class A:
    def test(self):
        print('Atest')
class B:
    def demo(self):
        print('Bdemo')
class   C(A,B):
    def demo(self):
        print('cdemo')
c=C()
c.test()
c.demo()
print(C.__mro__)#多重继承继承的是哪个类的方法，mro可以查看